Brush bristle reinforcement

ABSTRACT

Rotary brush bristles are locked together at intermediate portions by welding bristles together. The welds deteriorate with vibrations as the bristles wear to provide uniform bristle stiffness. Thin flexible, long-wearing bristles are stiffened to enhance their sweeping qualities.

United States Patent 1191 Horton et al.

11] 3,771,189 NOV. 13, 1973 [54] BRUSH BRISTLE REINFORCEMENT 3,114,925 12/1963 Charvat 15/159 A 3, 7 mm Avih K883"; Tmy 3,353,332 /i l5/1 8f) 0f Kemlwonh N1 3,357,03s 12/1967 Williamson et a]. 15/183 {7 Assisnee: lhnline Manufacturing p y FOREIGN PATENTS OR APPLICATIONS xemlwonh 754,953 8/1956 Great Britain 15/183 [22] Filed: Aug. 27, 1971 Primary ExaminerPeter Feldman [21] P 175,435 AttorneyCarroll B. Quaintance et al.

[52] U.S. Cl 15/179, 15/180, 15/183, [57] ABSTRACT 300/21 Rotary brush bristles are locked together at intermedi- 51 Int. Cl. A46b 13/02, A46b 3/02 ate portions by welding bristles togethen The welds [58] new Search 15/179 deteriorate with vibrations as the bristles wear to pro- 15/182 1831 1591 159 A; 300/21 vide uniform bristle stiffness. Thin flexible, longwearing bristles are stiffened to enhance their sweep- [56] References Cited ing qualities I UNITED STATES PATENTS 6 Claims, 6 Drawing Figures 2,239,686 4/1941 Owens 15/229 A 1 H 3,076,219 2/1963 Peterson 15/179 PMENTEUNUY 131975 SHEET 18? 2 w sN RO R 4 NE 3 2 TR 2. NOGL v 8 EHAU a 3 p $2) I U u\ p%%/% mmm Rm FIG 3 PMENIEDRmmsm R 3,771,189

' SHEET 28? 2 INVENTORS JOHN P HORTON AVIHU KAGEN TROY suns?) B WMQ ATTORNEYS mu m BRUSH BRISTLE REINFORCEMENT BACKGROUND OF THE'INVENTION The factors which effect the value of brushes are, basically, the life of the brushes, as well as the performance of the brushes during their life. This is a valid conclusion with respect to brushes used either as production tools or as road sweeping brushes.

Road sweeping brushes have special problems in the area of broom performance and life. A broom with fine diameter bristles normally lasts longer than a broom with coarse bristles. Stiffness of the individual filaments for given bristle lengths appears to be significant. Fine diameter filaments being less stiff do not bear as heavily against the abrasive surface (the road), and, therefore, last longer than thick, stiff bristles.

Finer diameter bristles do not sweep as well as thick, stiff bristles because fine bristles do not have the ability to impart kinetic energy to particles of dirt on the road surface, as do larger diameter filaments. However, a broom made up of a multiplicity of fine diameter filaments with the same weight of filaments in the broom does have the advantage that there are more active filament ends and, because of this, the broom has the ability to sweep finer particle sizes than would be accomplished in large diameter filament brooms.

Brushes have been constructed with bristles encapsulated in spongy material which holds the bristles together. The spongy material crumbles as the bristles vibrate and wear. The free length of the bristles between their free ends and the spongy matrix stays substantially the same throughout the life of the broom. Such brushes are not suitable for sweepers since the exposed free bristle ends do not have sufficient flicking capability to provide good sweeping characteristics. A sweeping brush must have a length of bristle which is sufficient so that the bristle may bend and store potential energy before releasing and imparting kinetic energy to the particles which are swept.

Brushes which are constructed of bristles which are bonded together over their entire length, or which are surrounded by relatively rigid material have a lack of flexibility which is required for good sweeping characteristics.

Crimped wire bristles knit together and interlock during use, lending mutual support. Plastic bristles, even when crimped, do not knit together. Unsupported thin bristles thus lack the stiffness and resilience necessary for good sweeping.

SUMMARY OF THE INVENTION Broadly, the invention concerns the use of joint means joining together groups of bristles at intermediate portions spaced from fixed ends and spaced from free ends.

In the present invention, bristle strengthening is accomplished with minimum procedural steps and expense and with no added material expense. Little or no extra material is used in the actual. joining together of the-bristles. Because little or no extra material is used to provide the joints, weights of the brush assemblies remain substantially the sameat the same time there is no extra deteriorating material that could necessitate extra waste sweeping and storing. Costs of production are significantly decreased since finer bristles may be used. Tooling expense incurred in adapting conventional apparatus to perform the bristle joining is kept to a minimum. The present invention provides combined advantages of prolonged brush bristle life and desirable bristle sweeping qualities which have heretofore been incongruent in sweeping brooms.

One feature of the invention concerns a particular joint means, namely welding. In groups of bristles, intermediate portions which are spaced from fixed ends and spaced from free ends are welded together using conventional pressure and heat generating and applying apparatus.

Bristle welding is accomplished during manufacture of the brush or after completion of the manufacturing. Metal wire bristles are welded together using conventional metal welding means. Thermosplastic materials are susceptible to thermal welding means. Alternatively, in case of thermoplastic bristles, friction welding or ultrasonic welding is used. In one form of the invention, polyolefin, typically polypropylene, bristles or nylon bristles are employed. Tufts of bristles are pressed together intermediate their ends and ultrasonic energy is applied to fuse compressed portions of the tufts.

In another form of the invention, bristles are destructably reinforced by bonding together groups of bristles at intermediate portions spaced from fixed ends and spaced from free ends with a separate adhesive or thermoplastic material. Alternatively, the intermediate portions of groups of bristles may be joined with destructible bands.

In all embodiments, the joint means are temporary, rather than permanent; after a period of brush vibration and wear, the joint means deteriorate and individual bristles become separate from one another. The deterioration of the joint means causes an increase in the free effective length of the bristles. Under continued sweeping-caused vibration, and under the bending stresses intensified by the wearing and shortening of the bristles, the joint means break or become weaker and less able to restrain the relative movement of individual bristles at their joined intermediate portions.

Reinforced bristles are assembled in a brush in several forms. For example, the bristle may be individually or collectively gathered along a straight or helical line or a ring before joining intermediate portions. Intermediate portions may 'be joined before bristles are mounted in a backing support. The bristles may be bunched together in tufts and then before being temporarily welded, bonded or banded. Preferably, the joining of intermediate bristle portions is accomplished across the bristles in directions generally perpendicular to elongated bristle directions. In welding and bonding, the joining may be done diagonally to the lengths of the bristles.

Bristles constructed according to the present invention are useful in most sweeping brooms. The destructibly reinforced bristles are especially useful in rotary powered brooms such as cylindrical brooms and disktype curb brooms.

One object of the invention is the provision of destructibly reinforced bristles which are joined for mutual support at medial portions spaced from supported and free ends of the bristles.

Another object of the invention is the provision of mutually supported groups of thermoplastic bristles temporarily interconnected by partial fusing intermediate ends of the bristles.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE DRAWINGS As shown inFIG. 1, cylindrical rotary brush 8 is mounted on rotary road sweeper 10. The brush assembly is mounted on plate 11 which is connected to driven axle 12 of road sweeper 10.

Adjacent bristles are interconnected intermediate their ends for mutual support by a plurality of welds 14.

FIG. 2 shows a perspective view of a circular brush disk 15 that can be mounted in a road sweeper. The brush section consists of an annular support 16 and bristles 17 which are attached to the support. The bristles 17 are shown divided into three portions. The outer portion 24 is the effective free length of the bristles 17 when the brush is initially placed in use and the welds are not broken. Welded portions 25 are located about one-third of the distance between support 16 and free ends 18 of the bristles 17. Welded portion 25 is shown running generally transverse to the bristle elongation. The innermost portion 26 of the bristles are relatively rigid until the welds in portion 25 deteriorate by vibration and wear. The effective lengths of the bristles 17 when the welds break become the lengths of the bristles between support 16 andthe worn ends. Preferably, the

welded portion 26 is not monolithic. Each bristle retains its major individual shape in the welded portion. Surfaces of the bristles are flowed together. Not all bristles need be united. Welding parameters are established so that bristles weld together in groups of ten to fifty. Vibration and wear causes the weld to progressively deteriorate toward the support. At the same time, some bristles or groups separate from the original large groups. The reduction of numbers of bristles bound in one group reduces the trend to increase stiffness with bristle shortening, thus tending to retain the initial flexibility.

In FIG. 3, the bristles 28 are mounted in plug 30 which has a throat 32 and a cap 34. A circular opening at the base of throat 32 reveals a hollow cylindrical wall which receives a tuft of bristles 28. Ends 22 of bristles 28 are forced into cylindrical opening 32 in plug 30, and the bristles are clamped while plug 30 is spun, creating frictional heat, melting and fusing the materials, 7

of pressure and the intensity and duration of the ultrasonic energy, all of the bristles in the tuft may be mutually joined, or the bristles may be joined in groups of ten or twenty. Small groups within the tufts, in the latter case, cooperate with other small groups for mutual support. I

In altemateforms, heat replaces the ultrasonic energy, and the heat is controlled so as to fuse only the surface portions of adjacent bristles.

While one weld 40 is sufficient, a second weld area 42 may be useful in the bristle tuft. When one weld is employed, it is usually suitable to place the weld about one-third of the distance from the fixed end of the bristles toward the free end.

As the welds progressively tear along the bristles toward the fixed end during use, more bristle length is added to the free length, maintaining the flicking action of the bristles. As the brushes wear, individual bristles separate fromthe welds and groups of bristles are broken down into several groups of smaller'numbers of bristles, tending to retain the elasticity uniform over the bristle wear.

In FIG. 4, a plurality of plugs 30 are shown assembled in strips 44. The strip is subsequently inserted in rotary brush holder either by sliding the strip in axial slat or by placing the strip in a cylindrical holder.

Welds 40, 42 and 46 may be at different heights to give the brush assemblies greater uniformity of wear. For example, in the illustrated case, weld 42 would first disintegrate, then weld 46 disintegrates before weld 40 disintegrates. The distance between the effective welds and the free ends of the bristles may be referred to as the active free bristle lengths. In the illustrated embodiment of FIG. 4, the active free lengths differ from tuft to tuft either in a random or a planned arrangement.

In FIG. 5, an elongated strip brush element is generally referredto by numeral 50. A support member 52 holds the brush in a rotary brush assembly. Bristles 54 are individually or collectively mounted in backing 52, and the bristles are either straight or bent plastic or wire bristles Weld 56, which is a single weld interconnecting all or the bristles, or which may be made up of several welds connecting adjacent bristles is positioned about onethird of the way between the fixed bristle ends 58' and free ends 59. As the brush wears, vibration causes weld 56 to reorganize in smaller groups of bristles and in individual bristles with a concurrent deterioration of the sitffness of the bristles so that sweeping characteristics and wear characteristics remain substantially uniform over the life of the brush.

As shown in FIG. 6, a gutter broom is constructed of a permanent disk-like plate 60 and a number of segments 62, which are fixed to the plate with bolts 63. Each segment has groups of bristles 64 which are welded together at areas 66 for mutual support of the bristles. During use, welds 66 break down as the bristles shorten, tending to maintain the sweeping and wear characteristics of thebristles substantially uniform over bristle life. I i

In one example of the invention, joint means are formed in polypropylene bristles by welding the bristles together with ultrasonic energy. Using a commercial power supply, for example a Brunson model J32A,with an ultrasonic horn which is,for example a one-half inch by 6 inch titanium horn with a gold coupling bar, and using air pressure of about 38 to 40 pounds per square inch to press the bar-shaped horn against the bristles, ultrasonic energy at about 20,000 cycles is applied for approximately 1 second, plus or minus one-quarter of a second. The compression of the bristles with the bar is maintained for approximately four seconds, and a suitable weld results. By decreasing air pressure, welding time and horn size, welds of slightly less duration are obtained so that the welds hold the bristles for about 400 to 500 miles of sweeping operations.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. Brush apparatus comprising:

A. a support means B. a plurlity of stiff bristles of thermoplastic material secured to the support means and extending therefrom, and

C. a number of temporary, destructible intermediate welds of the same thermoplastic material, each weld connecting a group of the bristles and formed as a fused integral part of said thermoplastic material which also forms the bristles, the weld being weaker than the bristles, whereby the welds eventually break as the bristles vibrate.

2. Brush apparatus according to claim 1 wherein the welds are ultrasonically fused portions of the bristles within each group of bristles, each weld being spaced from the support means and initially from the ends of the bristles remote from the support.

3. Brush apparatus according to claim 2, wherein the thermoplastic material is polyolefin material.

4. Brush apparatus according to claim 3 wherein the polyolefin material is polypropylene material.

5. Brush apparatus according to claim 4 wherein the major dimension of the welds extends generally perpendicular to the length of the bristles.

6. Brush apparatus according to claim 1 wherein the support means comprises a rotatable power-driven cylindrical center support. 

1. Brush apparatus comprising: A. a support means B. a plurlity of stiff bristles of thermoplastic material secured to the support means and extending therefrom, and C. a number of temporary, destructible intermediate welds of the same thermoplastic material, each weld connecting a group of the bristles and formed as a fused integral part of said thermoplastic material which also forms the bristles, the weld being weaker than the bristles, whereby the welds eventually break as the bristles vibrate.
 2. Brush apparatus according to claim 1 wherein the welds are ultrasonically fused portions of the bristles within each group of bristles, each weld being spaced from the support means and initially from the ends of the bristles remote frOm the support.
 3. Brush apparatus according to claim 2, wherein the thermoplastic material is polyolefin material.
 4. Brush apparatus according to claim 3 wherein the polyolefin material is polypropylene material.
 5. Brush apparatus according to claim 4 wherein the major dimension of the welds extends generally perpendicular to the length of the bristles.
 6. Brush apparatus according to claim 1 wherein the support means comprises a rotatable power-driven cylindrical center support. 